1. Field of the Invention
This invention relates to an ultraviolet irradiation device to irradiate an ultraviolet curable protective tape joined to a surface of the semiconductor wafer with ultraviolet rays for reducing adhesive force thereof prior to separation of the protective tape.
2. Description of the Related Art
Examples of methods for use in thinning a semiconductor wafer (hereinafter, simply referred to as a “wafer”) include a mechanical method such as grinding and polishing or a chemical method such as etching. These methods are used for processing a rear face of the wafer to obtain a thinner thickness thereof. Upon processing the wafer through these methods, the protective tape is joined to a surface of the wafer for protection with a wiring pattern formed thereon. The rear face of the ground wafer with the protective tape joined thereto is adhesively held on a ring frame via a support adhesive tape. Subsequently, the protective tape is separated from the surface of the wafer held on the ring frame.
The following method is known for separating a protective tape. That is, a separation tape having strong adhesive force is joined to a surface of a protective tape, and then the separation tape is separated. Consequently, the protective tape may be separated from a surface of a wafer together with the separation tape. See JPH05-63077A.
Moreover, an ultraviolet curable protective tape is used, and ultraviolet rays are applied to the protective tape prior to separation thereof, thereby obtaining the protective tape having reduced adhesive force. A device for irradiating the protective tape with ultraviolet rays is configured as following. That is, a wafer with the protective tape joined thereto is suction-held on a suction table capable of reciprocating along a guide rail. The ultraviolet irradiation device arranged in an upper side irradiates the protective tape with ultraviolet rays during reciprocation of the suction table. The ultraviolet irradiation device has ultraviolet light emitting diodes (hereinafter, appropriately referred to as “diodes”) arranged in rows and columns. See JP2006-40944A.
The above conventional device, however, has the following problems.
Specifically, the ultraviolet irradiation device need to reciprocate the suction table on the guide rail, which may result in an enlarged area for installation of the device.
In addition, uniform intensity of illumination throughout the surface of the wafer during in-line reciprocation on the guide rail requires diodes arranged in rows and columns beyond a diameter of the wafer. As a result, another problem may arise that the device increases in size and weight.